The present invention relates to a motor control device used for a magnetic recording and reproducing apparatus such as VTR, etc. and a magnetic recording and reproducing apparatus using the same, and in particular to a motor control device capable of rotating stably a motor, even in the case where there are non-uniform components in a rotational speed detection signal from the motor and a magnetic recording and reproducing apparatus using the same.
In a motor control device used for VTR, etc., motor control by digital signal processing is used from points of view that high density integration is easy, that performance and reliability are high, that deregulation can be omitted, etc. In this control by digital signal processing, rotation speed and rotation phase of the motor is detected in a digital manner to compare them with a speed and a phase, which are control targets, respectively. After error signals representing differences thus obtained have been subjected to operation and processing, they are feedback to the motor so as to rotate the motor with a desired speed and phase.
As relating techniques, there are known those reported in documents relating to software servo techniques for VTR, such as e.g. "Technical Reports of the Television Society of Japan", Vol 12, No 17, pp 37 to 42 (1988), "Preliminary Reports of Annual Meeting 1991 of the Television Society of Japan" pp. 155 to 156, etc. These are techniques, by which a kind of comb-shaped filter is inserted into a speed control system or a drum, utilizing the fact that almost all non-uniform components in frequency signals proportional to rotation speed of the drum (hereinbelow called DFG signals) are periodical, in order to eliminate non-uniform components in the DFG signals.